Kelvin-Helmholtz Instability of the CME Reconnection Outflow Layer in the Low Corona

Claire Foullon, Erwin Verwichte, Katariina Nykyri, Markus J. Aschwanden, Iain G. Hannah

Research output: Contribution to journalArticlepeer-review

Abstract

New capabilities for studying the Sun allow us to image for the first time the magnetic Kelvin–Helmholtz (KH) instability developing at the surface of a fast coronal mass ejecta (CME) less than 150 Mm above the solar surface. We conduct a detailed observational investigation of this phenomenon, observed off the east solar limb on 2010 November 3, in the EUV with SDO/AIA. In conjunction with STEREO-B/EUVI, we derive the CME source surface position. We ascertain the timing and early evolution of the CME outflow leading to the instability onset. We perform image and spectral analysis, exploring the CME plasma structuring and its parabolic flow pattern. As we evaluate and validate the consistency of the observations with theoretical considerations and predictions, we take the view that the ejecta layer corresponds to a reconnection outflow layer surrounding the erupting flux rope, accounting for the timing, high temperature (∼11.6 MK), and high flow shear (∼680 km s−1) on the unstable CME northern flank and for the observed asymmetry between the CME flanks. From the irregular evolution of the CME flow pattern, we infer a shear gradient consistent with expected spatial flow variations across the KH-unstable flank. The KH phenomenon observed is tied to the first stage of a linked flare–CME event.

Original languageAmerican English
JournalThe Astrophysical Journal
Volume767
DOIs
StatePublished - Apr 8 2013

Keywords

  • instabilities
  • plasmas
  • solar-terrestrial relations
  • Sun: corona
  • coronal mass ejections

Disciplines

  • Astrophysics and Astronomy
  • The Sun and the Solar System

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